Fatty acids are constituents of fats and lipids. Fats and lipids are found in all living organisms and are essential for their growth, survival and reproduction. Saturated fatty acids are those in which all the carbon bonds in the molecule are connected to each other only by single bonds. Unsaturated fatty acids contain carbon atoms, one or more of which are connected by double bonds. Fatty acids with more than one double bond are called polyunsaturated fatty acids (PUFAs). PUFAs vary in the position of the first double bond from the methyl end of the fatty acid molecule, the number of carbon atoms in the fatty acid and the number of double bonds. PUFAs in which the double bond occurs at the third carbon from the methyl end of the fatty acid molecule are called omega-3 fatty acids. Examples are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), DHA contains 22 carbon atoms and 6 double bonds. It is represented as 22:6w3 EPA contains 20 carbon atoms and 5 double bonds, it is represented as 20:5w3 (Wailis, J. G. et al. 2002. Trends in biochemical Sciences 27: 467-473). Several of the PUFAs are extremely important for human health. DHA is extremely important in the brain development of infants, retinal vision, prevention of cardiovascular and many other disease states (Bajpai P. and P. K. Baipai. 1993. Journal of Biotechnology 30: 161-183; Barclay, W. R. et al. 994. Journal of Applied Psychology 6: 123-129; U.S. Pat. No. 9,428,913). DHA is known to be important in development, maturation and reproduction of crustaceans, including many animals of importance in aquaculture such as prawns (Harrison, K. E. 390, Journal of Shellfish Research, 9: 1-28). Therefore, it is important to incorporate DHA and EPA in human and animal foods.
Polysaccharides are polymers of different kinds of sugars. Many polysaccharides are of biotechnological use. Thus, for example, cellulose and starch are polymers of glucose, while agar-agar, which is used in jellies and for microbiology research, is a polymer produced by the marine sea weeds, the red algae. The marine sea weeds, the brown algae produce the polysaccharides alginates. Polysaccharides are produced by a wide variety of plants, animals and microorganisms. Microorganisms such as cyanobacteria, heterotrophic bacteria and fungi produce polysaccharides which are secreted out into the growth medium outside their cells. Polysaccharides thus secreted out into the liquid culture growth medium are called extracellular polysaccharides (EPS). There are several examples of the biotechnological uses of EPS.
Many such polysaccharides contain sulphate groups and are termed sulphated polysaccharides. Sulfated polysaccharides are also of biotechnological importance, for example, as blood anticoagulants and antiviral compounds (K. Sogawa et al., 1998, Marine microalgal polysaccharides induces apoptosis in the human lymphoid cells. Journal of Marine Biotechnology 6:35-38). Several papers have described the application of extracellular sulfated polysaccharides from organisms such as the cyanobacterium Aphanocapsa halophytia and the red alga Porphyridium sp. (S. Geresh and S. Arad, 1991, Bioresource Technology 38: 195-201; T. Matsunaqa et al., 1998, Applied Microbiology and Biotechnology 45: 24-27). Sulphated polysaccharides thus have the potential for various applications.
Thraustochytrids are unicellular marine organisms that are heterotrophic. i.e., they require organic carbon for their nutrition similar to fungi and bacteria.
The major genera are Thraustochytrium, Schizochytrium and Ulkenia, which correspond in morphology to cultures deposited at the American Type Culture Collection bearing Accession Nos. ATCC 28210, 24473, 34304, 28209 and MYA-1381. The major current commercial sources for the production of DNA are fish oil single-celled algae and the single-celled protists, the thraustochytrids. Thraustochytrids are now known to be commercially important for the production of the polyunsaturated fatty acid and docosahexadnoic acid (DHA). The biotechnological importance of thraustochytrids for the production of DHA has been reviewed by Lewis et al. (Lewis, T. E, et al. 1999. Marine Biotechnology 1: 580-587).
U.S. Pat. Nos. 5,130,242, 5,340,742 and 5,340,594 describe a process for the production of whole cells or products extracted from whole cells of thraustochytrids with high amounts of DHA, which can be used to supplement processed foods as a nutritional supplement, or to fish and animal feeds to enhance DHA contents and to use the extracted products in nutritional pharmaceutical and industrial applications. However, this patent does not encompass using the spent culture filtrate for the production of any products, including extracellular polysaccharides. These patents describe the process of growing thraustochytrids but it does not teach the simultaneous production of lipids and extracellular polysaccharides.
Japanese Patent No. 9633263 (1966) describes a strain of a thraustochytrids, which can be grown in fermentors, the cell biomass harvested can be used for application in the food industry such as food additives, nutritional supplements as additives for infant milk formula, feedstuffs and drug additives, where an addition of DHA is resulted because the cells have high amounts of DHA. However, this patent also does not encompass using the spent culture filtrate for the production of any products, including extracellular polysaccharides.
The U.S. Pat. Nos. 5,518,918, 5,688,500, 5,908,622, 6,103,225, 6,566,123 5,374,657 and 5,550,156 and the European Patent EP 0669809 disclose a process for growing thraustochytrids in a growth medium containing non-chloride containing salts, such that cell aggregates are produced which are useful as food products in aquaculture. Each of these patents discusses different compositions of the aquaculture feed. However, these patents do not encompass using the spent culture filtrate for any products, including extracellular polysaccharides. These patents describe the process of growing thraustochytrids but it does not teach the simultaneous production of lipids and extracellular polysaccharides.
The U.S. Pat. Nos. 5,985,348 and 6,177,108 disclose a process for growing thraustochytrids in a culture medium, harvesting the whole cell biomass and feeding the biomass or oils extracted from them to milk producing animals to enhance DHA contents in milk produced from them. However, these patents do not encompass using the spent culture filtrate for any products, including extracellular polysaccharides.
The U.S. Pat. Nos. 6,054,147, 6,716,460 and the European Patent. EP1021083 disclose a feeding regime for increasing omega-3 fatty acids in poultry meat or to improve the flavor, tenderness and overall consumer acceptability of poultry meat by feeding poultry animals with cell biomass or oils extracted from the cell biomass of thraustochytrids grown in suitable nutrient media. However, the patents do not encompass using the spent culture filtrate for the production of any products, including extracellular polysaccharides.
The U.S. Pat. Nos. 6,582,941 and 6,607,900 relates to a strain of thraustochytrids which produces a high amount of the omega-3 fatty acid docosapentaenoic acid in their cell biomass, whereby the organism is grown in suitable nutrient media and the cell biomass, or extracts of the cell biomass with the fatty acid can be used in composition of various feedstuffs for increasing the contents of docosapentaenoic acid. However, the patents do not encompass using the spent culture filtrate for any products, including extracellular polysaccharides. These patents do not teach the present invention.
Thus, in all the above prior art known processes relating to the production of DHA from thraustochytrids, the spent culture medium is discarded. Particularly, the culture filtrate is not used for the production of commercially useful extracellular polysaccharides (EPS). Therefore their use is limited to the preparation of only a single product.
Thus, in all the above mentioned known prior art processes relating to the production of commercially useful extracellular polysaccharides from various microorganisms, the cell biomass is discarded. Particularly, the cell biomass is not used for the production of the polyunsaturated fatty acid, DHA. Therefore, their use is limited to the preparation of only a single product.
Except as otherwise indicated, the disclosure of all patents, patent applications (and any patents which issue thereon, as well as any corresponding published foreign patent applications), and publications mentioned throughout this description are hereby incorporated by reference herein. It is expressly not admitted, however, that any of the documents incorporated by reference herein teach or disclose the subject matter of the present invention.